This invention relates, in general, to processing within a computing environment, and in particular, to monitoring events that occur during processing.
Over the years, different monitoring tools have been used to monitor processing events. One such tool is a Monitor Call (MC) instruction used for monitoring processing within z/Architecture® systems, offered by International Business Machines Corporation. The Monitor Call instruction provides programs with the ability to monitor key areas of interest, which are represented by monitor classes and monitor masks. The monitor masks allow the control program (e.g., operating system) to enable one or more of sixteen possible monitor classes. When a Monitor Call instruction is executed that specifies an enabled monitor class (i.e., mask bit for specified class is set), a monitor event program interruption occurs, and the control program can record information based on a monitor code specified in the instruction. When a Monitor Call instruction is executed, but the specified monitor class does not correspond to an enabled monitor mask bit, the instruction acts as a no-operation (NOP).
The Monitor Call instruction is used, for instance, to count the executions of instrumented code paths. The counting is performed using a Count program. The Count program has been used for years to determine the frequency of various key operating system events, including, as examples, supervisor calls (SVCs), locking, interruptions, storage allocation and release, scheduling, enqueuing and dequeuing, and so forth.